The invention generally relates to a handle for a medical instrument comprising at least one movable grip element and a coupling portion through which a shaft can be or is joined with the handle. The movable grip element is joined or can be joined with a force transmission element axially movable in the direction of the longitudinal axis of the shaft for translating motion of the at least one movable grip element into a linear motion of the force transmission element.
Such a handle is known for example from the German firm catalogue of the company Karl Storz GmbH and Co., Tuttlingen, xe2x80x9cKarl Storz-Endoskopexe2x80x9d, volume xe2x80x9cEndoskopische Chirurgiexe2x80x9d, second edition January 1994, page DGC 5/1 A.
Medical instruments are employed for various types of surgical operations on the human and animal body, in particular in minimal invasive surgery. Such instruments, for example tubular shaft instruments, can be configured as forceps, for example preparing or grasping forceps, forceps for cutting tissue, or as stamping or punching tool or the like. Depending on their varying function, the instruments differ in the corresponding configuration of the tools at the distal end. Cutting, grasping or punching tools can be provided at the distal end, where such an instrument comprises at least one movable tool, for example in the form of a jaw or a jaw part. However, such instruments can also comprise two or more movable tools at the distal end.
The instruments have a handle at the proximal end of the shaft to actuate the at least one movable tool. The shaft of the instrument is normally releasably or non-releasably joined with a coupling portion of the handle. In addition, the handle comprises at least one movable grip element for providing the actuation of the at least one movable tool at the distal end of the shaft. To actuate the at least one movable tool at the distal shaft end, the at least one movable grip element of the handle is joined in force-locking manner with the at least one movable tool through a force transmission element axially movable in the direction of the longitudinal axis of the shaft, for example a push and pull rod. Thus, motion of the movable grip element, for example a rotation or axial motion, is translated into axial relative motion of the force transmission element with respect to the shaft and finally motion of the movable tool.
A handle of the above-mentioned type is known in various configurations. The handle usually comprises a second grip element which is either stationary and fixed to the shaft or is also movable. Such a handle can also be formed as a scissors handle, where the two grip elements extend sidewards from the shaft of the instrument, as illustrated in the above-mentioned company brochure. In the sense of the present invention, the handle however can also be formed like a pistol grip element or like a bar grip element held in the fist of one hand.
Common to all these types of handles is that the handles in the joined condition with the shaft have a fixed, invariable angular position with respect to the shaft, i.e. the handle axis and the longitudinal axis of the shaft form a fixed angle with respect to one another.
However, a handle having a fixed angle with respect to the axis of the shaft is not always adapted to the requirements of the operating doctor with respect to its handling properties. Different doctors prefer different grip element orientations of the same type of handle with respect to the shaft depending on what they are accustomed to. To always have the handle with the optimal ergonomic angular position with respect to the shaft, it would therefore be necessary to have a set of several handles for each type of handle, which have different angular positions when joined with the shaft, so that the doctor can select the most ergonomic and optimal handle for himself. If the handles are not exchangeable, this means that for each instrument, an entire set of such instruments with differently angled handles must be available.
In addition, it can be desirable or necessary in some cases that the handle of the same instrument should take on different angular positions with respect to the shaft during the operation to have the most comfortable and therefore safest hand position for the operation procedure to be carried out. This would mean with the known handles, assuming a complete set were available, that the handle would have to be exchanged several times during the operation or with the nonexchangeable handles, the entire instrument would have to be exchanged which would substantially prolong the operation.
Accordingly, the known handles have disadvantages with respect to their ergonomic properties.
The object of the present invention is therefore to provide an improved handle of the above-mentioned type, which allows an ergonomic handling of the instrument, without having to exchange the handle or possibly even the entire instrument.
This object is achieved according to the invention by providing a handle for a medical instrument, comprising:
at least one movable grip element for being joined with a force transmission element axially movable in direction of a longitudinal axis of a shaft of said instrument to transfer motion of said at least one movable grip element into linear motion of said force transmission element;
a coupling portion for joining said shaft with said handle, said coupling portion being pivotal relative to a handle axis about at least one first pivot axis running transversely to the longitudinal axis of said shaft;
a lever arrangement for joining said at least one movable grip element with said force transmission element, comprising at least two double-arm levers, a first lever of which being pivotal about a first axis stationary with respect to said handle and a second lever of which being pivotal about a second axis stationary with respect to said coupling portion, and said two levers being joined to another to be pivotal with respect to one another about said first pivot axis.
According to the invention, the coupling portion through which the handle is joined or can be joined with the shaft is pivotal, so that the handle can be disposed in different angular positions with respect to the shaft. Preferably, the adjusted angle of the handle can be locked for rigid connection of the shaft to the handle to then employ the instrument in an operation procedure. With the pivotal configuration of the coupling portion, the doctor himself can adjust the optimal ergonomic angle between the handle and the shaft, without having to exchange the handle or even the entire instrument. The handle according to the invention is therefore substantially improved with respect to ergonomics.
In providing the adjustability of the handle axis with respect to the longitudinal axis of the shaft, the problem arises that the force transmission element must be joined with the movable grip element such that the motion of the movable grip element can be translated into axial motion of the force transmission element for all angles of the handle. In the conventional handles, the force transmission element, normally formed as a push and pull rod, is directly joined with the movable grip element at its proximal end. This type of connection of the force transmission element however cannot be retained if the handle is placed at an angle with respect to the shaft. This would mean that the force transmission element in the area of the pivot axis of the coupling portion would also have to be deflected, angled or bent and a compensation for the length of the force transmission element would also be provided depending on the angle of the shaft with respect to the handle axis. The use of a flexible transmission element, for example in the form of a Bowden cable, which could adapt to the different angles in the angled region, would have the disadvantage that increased friction would arise at the deflection position. Also, when angling the shaft with respect to the handle, the movable grip element would be undesirably moved due to the constant length of the force transmission element. A Bowden cable has the further disadvantage that impurities could collect between the mantel and the flexible wire of the Bowden cable, which would be difficult or impossible to remove. Furthermore, only limited compressive forces can be translated to the movable tool with a Bowden cable.
In contrast, a force transmission mechanism is provided according to the invention between the movable grip element and the force transmission element, by which the movable grip element is or can be joined with the force transmission element by a lever arrangement. The arrangement comprises at least two double-arm levers, the first lever being pivotal about an axis stationary with respect to the handle and the second lever being pivotal about an axis stationary with respect to the coupling portion. Both levers are joined in force-locking manner with one another and pivotal about a first pivot axis with respect to one an other.
Thus instead of connecting the force transmission element directly with the movable grip element passing the first pivot axis, the handle according to the invention provides a lever arrangement comprising at least two double-arm levers between the movable grip element and the force transmission element.
Force from the movable grip element is first transmitted to the first lever, so that it is pivoted about its axis fixed to the handle and through the connection causes the second lever to pivot about it s axis fixed to the coupling portion, which in turn is joined with the force transmission element, so that it can be translated in the axial direction of the shaft. Due to the fact that the two levers are pivotal about the first pivot axis and with respect to one another, the two levers can take on an angular position relative to one an other which corresponds to the respective adjustment angle of the shaft with respect to the handle axis. Thus the same force transmission conditions are present for all angular positions, because the force transmission characteristics are only determined by the configuration of the two levers. In particular, this configuration of the force transmission mechanics has the advantage that the force transferred from the movable grip element to the force transmission element is independent of the adjustment angle between the shaft and the handle axis. A further advantage is that when actuating the movable grip element and transmitting force to the lever arrangement, the shaft can be pivoted with respect to the handle axis without having to release or inactivate the movable grip element.
In a preferred embodiment, the movable grip element is joined with a coupling rod axially displaceable in a longitudinal direction thereof, which in turn is joined with a first lever arm of the first lever.
Applying force from the movable grip element to the lever arrangement through an axially displaceable coupling rod has the advantage that applying force from the movable grip element via the coupling rod is also possible when the grip element is arranged remotely from the lever arrangement.
In a further preferred embodiment, the coupling rod is arranged such that its longitudinal axis lies on a line intersecting the first pivot axis.
This has the particular advantage that when the movable grip element is actuated, the coupling rod does not exert a torque on the coupling portion, which is pivotal about the first pivot axis. In other words, the play of the coupling portion about the first pivot axis is not transmitted to the movable grip element, so that the mechanics of force transmission from the movable grip element to the force transmission element is nearly free of play.
In a further preferred embodiment, the first lever and the second lever are joined with one another by a journal having a pivot joint, whose pivot axis is coincident with the first pivot axis.
This feature provides a constructively simple and particularly advantageous pivotal connection about the first pivot axis between the first lever and the second lever. The journal can be arranged such that its longitudinal axis is coincident with the first pivot axis. In the simplest case, the journal can consist of two journal halves joined with one another by a pivot joint, which has a rotational degree of freedom about the first pivot axis.
Preferably, the first lever converts axial motion of the coupling rod into axial motion of the journal in the direction of the first pivot axis and the second lever translates axial motion of the journal into axial motion of the force transmission element in the direction of the longitudinal axis of the shaft.
This feature allows a kinematically favorable force transmission from the coupling rod through the lever arrangement to the force transmission element. Since the lever arrangement comprises at least two levers, the lever arrangement together with the journal can be conveniently configured such that axial motion of the coupling rod is converted by the first lever into axial motion of the journal transversely to the motion direction of the coupling rod, where the axial motion of the journal can then be converted by the second lever into motion of the force transmission element transversely to the movement direction of the journal and thus in the direction of the longitudinal axis of the shaft.
In a further preferred embodiment, the coupling portion additionally is pivotal relative to the handle axis about a second pivot axis running transversely to the first pivot axis and transversely to the longitudinal axis of the shaft, and the first lever and the second lever are joined to be pivotal with respect to one another about the second pivot axis.
Of particular advantage is that the shaft is provided with two degrees of freedom with respect to the handle, i.e. the shaft can take on different angular positions with respect to the handle about the first pivot axis and in addition also about the second pivot axis. Consequently, the instrument equipped with the-present handle can be even better adapted to the special requirements of the doctor operating the instrument and to the special requirements of the operative procedure. Thus, the ergonomics of the handle of the present invention is even further improved.
Preferably, a third double-arm lever is arranged between the first lever and the second lever, where the first lever is joined with the third lever to be pivotal about the first pivot axis and the second lever is pivotally joined with the third lever to be pivotal about the second pivot axis.
In constructively simple and advantageous manner, this feature provides force transmission mechanics for the configuration of the handle where the coupling portion is pivotal with respect to the handle axis about two pivot axes. A force transmission is achieved independent of the respective angle of the shaft with respect to the handle axis, also for a handle with two degrees of freedom of the coupling portion with respect to the handle axis.
In a further preferred embodiment, the first lever and/or the second lever and/or optionally the third lever are formed approximately as an L-shaped angle.
The advantage is that the force introduction into the lever and the force transmission out of the lever can take place at a right angle with respect to the corresponding lever arm, i.e. with the maximum possible torque.
In a further preferred embodiment, the first lever and the second lever and optionally the third lever are configured with respect to their lever arm ratios, such that a force enhancement results in the force transmission from the movable grip element through the lever arrangement to the force transmission element.
This feature is of particular advantage in such instruments when hard tissue is to be removed from the human or animal body, for example bone tissue. By proper selection of the lever arm ratio, such hard tissue can easily be removed with only a little hand force of the doctor.
However, it can also be preferred that the first lever and the second lever and optionally the third lever are configured with respect to their lever arm ratios, such that the lever arrangement transmits a constant or a smaller force.
This can be of advantage for example when the instrument comprises tools for grasping tissue, for example to displace organs or vessels in the body, i.e. instruments by which the doctor must carefully apply force with his hand to avoid damage to vessels or organs.
In a further preferred embodiment, the shaft is or can be joined with the coupling portion pivot about its longitudinal axis. This feature has the advantage that the shaft can not only be angled with respect to the handle, but additionally is rotatable about its longitudinal axis. The tool or tools at the distal end of the shaft can then be additionally adjusted in any rotary position with respect to the handle. The handle of the present invention in this embodiment allows a total of three degrees of freedom of motion relative to the shaft, where the instrument equipped with the handle can be even better adapted to the given requirements of the operation.
In a further preferred embodiment, the force transmission element is directly or indirectly joined with the second lever through a ball and socket connection.
This feature is of particular advantage with the above embodiment where the shaft is or can be pivotally joined with the coupling portion about its longitudinal axis, since the force transmission element also rotates when rotating the shaft about its longitudinal axis because the ball and socket connection with the second lever allows such rotation. The force transmission element is joined with the at least one movable tool at the distal end of the shaft and on the other hand, at least one movable tool in operational condition of the instrument is fixedly joined with the shaft. Consequently, a rotational capability of the shaft about its longitudinal axis is achieved in constructively simple manner because no additional elements are required to connect the force transmission element pivotally with the at least one movable jaw.
In a further preferred embodiment, the coupling portion can be locked by means of a locking mechanism in a plurality of angular positions with respect to the handle axis in an angular range of up to 240xc2x0 about the first pivot axis and/or about the second pivot axis.
With this feature, the handle can be pivoted in an angular range between about xe2x88x92120xc2x0 and about +120xc2x0 about the first pivot axis and/or about the second pivot axis and can be locked in at least two, preferably however a plurality of pivot positions, whereby the ergonomics of the handle with respect to the shaft angle can be adapted over a large angular range to the desired requirements of the doctor. The pivotal range however can also be smaller, for example between xe2x88x9290xc2x0 and +90xc2x0 or between 0xc2x0 and +120xc2x0 just to mention a few examples.
Preferably, the locking mechanism comprises a locking nose engageable with notches in the coupling portion and the locking mechanism further comprises a push button such that the locking nose is disengageable with the respective notch by depressing the push button.
This type of locking or unlocking the coupling portion leads in advantageous manner to pivoting and locking characteristics of the handle which are easy to manipulate.
In a further preferred embodiment, the coupling portion comprises a seat for the shaft for releasably joining the shaft with the coupling portion.
The advantage is that the shaft can be removed from the coupling portion and therefore from the handle, where the handle and the shaft can be better cleaned when separated.
In a further preferred embodiment, the coupling portion comprises a seat for a proximal end of the force transmission element, where the seat is axially movable and joined with the second lever.
In this embodiment, the force transmission element is not directly joined with the second lever, but through a separate receptor provided for the proximal end of the transmission element. The advantage is that the connection between the force transmission element and the second lever can be made very easily. In addition, the embodiment allows the possibility of connecting the force transmission element releasably with the handle.
Preferably, the seat comprises a locking mechanism for releasably joining the force transmission element with the coupling portion. The advantage is that the force transmission element can be removed from the coupling portion and thus from the handle, where the force transmission element after removal from the handle can be easily cleaned.
An instrument according to the present invention, which comprises a shaft, at least one movable tool at the distal end of the shaft and a force transmission element arranged to be axially movable with respect to the shaft for actuating the at least one movable tool, is preferably and advantageously equipped with a handle of the invention according to one or more of the above embodiments.
Preferably, the shaft and/or the force transmission element is releasably joined with the handle and/or the force transmission element is releasably joined with the shaft. Due to the releasable configuration of both the shaft and the force transmission element, the shaft, the force transmission element and the handle can be disassembled from the instrument, where each component can then be efficiently cleaned.
Further features and advantages will be apparent from the following description and the attached drawings.
It will be understood that the above-mentioned features and those to be discussed below are not only applicable in the given combinations, but may also be employed in other combinations or taken alone without departing from the scope of the invention.
Embodiments of the invention are illustrated in the drawings and will be discussed in more detail below.